Cardiomyopathy is a generic term used to describe conditions in which lesions develop in the myocardium of the heart. The disease may be classified as secondary or primary. The secondary cardiomyopathies are those which are associated with an identifiable disease condition. Primary cardiomyopathy is a diagnosis which is made only after all known causes have been considered and eliminated. Primary cardiomyopathy is the most common form of the disease in Western countries.
In general, there are three clinical classifications of primary cardiomyopathy: dilated (congestive), restrictive and hypertrophic. Dilated cardiomyopathy is characterized by the dysfunction of left and/or right ventricular function. This condition leads to cardiac enlargement. Restrictive cardiomyopathy is characterized by abnormal diastolic function associated with excessively rigid ventricular walls. Hypertrophic cardiomyopathy is characterized by left ventricular hypertrophy.
Present methods available for the evaluation of the cardiomyopathies include chest roentgenogram, electrocardiogram, echocardiogram, radionuclide studies and cardiac catheterization. Although the characterization of the cardiomyopathies on the basis of clinical presentation is useful, a method that would enable an etiologic diagnosis is preferable. In many cases, such a diagnosis is not possible.